Upload location took very long time - revamp the validationcode

CREATE TABLE `TMP_VALIDATIONCODE` (
`VALIDATIONCODE` VARCHAR(4) NOT NULL,
`seq` INT,
PRIMARY KEY (`VALIDATIONCODE`)
);

-------------------------------------------------

DELIMITER $$

DROP PROCEDURE IF EXISTS `FLUX_SPCUS_VALIDATIONCODE`$$

CREATE PROCEDURE `FLUX_SPCUS_VALIDATIONCODE`()
BEGIN
SET @i = 0;
WHILE @i < 26 DO

SET @j = 0;
WHILE @j < 26 DO

SET @k = 0;
WHILE @k < 26 DO

SET @l = 0;
WHILE @l < 26 DO

INSERT INTO TMP_VALIDATIONCODE (VALIDATIONCODE, seq) VALUES
(CONCAT(CHAR(@i + 65), CHAR(@j + 65), CHAR(@k + 65), CHAR(@l + 65)), RAND()*32767);
SET @l = @l + 1;
END WHILE;
SET @k = @k + 1;
END WHILE;
SET @j= @j + 1;
END WHILE;
SET @i = @i + 1;
END WHILE;
END$$

DELIMITER ;

--------------------------------------------------

CALL FLUX_SPCUS_VALIDATIONCODE;

DELETE A FROM TMP_VALIDATIONCODE A
INNER JOIN BAS_LOCATION B ON A.VALIDATIONCODE = B.VALIDATIONCODE;

-------------------------------------------------

CREATE
DEFINER = 'app'@'%'
TRIGGER app.TRG_GENERATE_VALIDATEION_CODE
BEFORE INSERT
ON app.BAS_LOCATION
FOR EACH ROW
BEGIN
DECLARE sValidationCode varchar(10);
DECLARE nCount int;

SET sValidationCode := '*';
SELECT ValidationCode
into sValidationCode
FROM TMP_VALIDATIONCODE
order by seq
limit 1 for update;
delete from TMP_VALIDATIONCODE where ValidationCode = sValidationCode;

SET new.validationCode = sValidationCode;
END